Recently, development of an organic EL element which is a thin solid light emitting element has been promoted. For example, a lighting device employing such an organic EL element as its light source has been proposed (e.g., see document 1 [JP 2007-265805 A]).
The lighting device disclosed in document 1 includes a light emitting unit constituted by organic EL elements, and a DC power source configured to supply a desired DC voltage to the light emitting unit. However, the organic EL element has a capacitance component. Therefore, there is a problem that application of a voltage to the organic EL element is likely to cause an excess rush current to flow into the organic EL element.
In consideration of this problem, in the lighting device disclosed in document 1, an inductor which serves as a current limiting device is interposed between the DC power source and the organic EL element to decrease the rush current which flows through the organic EL element when a voltage is applied.
In the aforementioned prior lighting device, suppression of the rush current flowing through the organic EL element is achieved by the inductor connected between the DC power source and the organic EL element. However, connection of the inductor is likely to cause a distortion in a current waveform and an increase in a loss.